This invention relates to dock positional platforms or elevators of the vertical lift and descent type as employed in heavy-duty loading applications, and more particularly, relates to an improved bi-elevational platform adjustable for both vertical lift positions and angular lift positions.
It is common practice to employ so-called heavy-duty vertically adjustable scissor-action platforms or elevators in the dockside handling of cargos and dead loads. These vertical platforms are conventionally actuated by hydraulic cylinders directly attached to the platform which can be selectively actuated to control the vertical lift and descent either under load or without load. In particular applications for dockside handling of cargo or bulk loads, it becomes more desirable to provide that the platform be made to ascribe an angle of lift as referenced from the horizontal. The stationary angular position therefore is more convenient in lieu of providing many lifts and descents over a relatively small vertical height, as compared to the maximum vertical lift capacity of the platform.
Platforms are then provided which move vertically while maintaining a level horizontal loading surface and platforms are also provided which are positioned to assume a desired angle of deviation from the horizontal wherein the loading surfaces are so-angled. However, it is thought that heretofore it has not been common practice to provide such a loading elevator optionally featuring both vertical lift positions and angular lift positions, hereinafter sometimes referred to as bi-elevational or dual positional platforms.
The present invention provides improved bi-elevational platform lift apparatus comprised of base structure means, movable platform structure means, intermediately disposed scissor-acting or criss-crossed expandable first support structure means, first hydraulic actuator power means attachable to the first support structure means and being effective through hydraulic cylinder expansion to cause scissor-action expansion from a closed position of the first support structure means and resulting vertical movement of the platform structure means, second support structure means pivotably attached to the first support structure means and having the free end portion thereof movable against the platform structure means with the first support structure means in said closed position, and second hydraulic actuator power means attachable to the second support structure means and being effective through hydraulic cylinder expansion to cause pivotable movement of the second support structure means against the platform structure means resulting in angular movement thereof.
It is therefore an object of the present invention to provide an improved bi-elevational platform lift movable to desired vertical lift and descent positions and desired angular lift and descent positions.
It is another object of the invention to provide separately actuable support structure means to provide either vertical lift adjustments or angular lift adjustments.
It is yet another object to provide conventional scissor-action support structure means powered by hydraulic cylinder means to accomplish vertical lift and descent movements of the platform structure means.
It is still another object to provide improved pivotable support structure means powered by hydraulic cylinder means to accomplish angular lift and descent movements of the platform structure means.
It is a further object to provide angular lift movements of the platform structure means with the scissor-action support structure means in a fully closed or collapsed position thereof.
It is still further object of the invention to provide that the pivotable support structure means has its free end portion engageable with and movable against a selected edge portion of the platform structure means to effect selective lifting thereof with respect to an oppositely disposed edge portion thereof.